Process of making dental tooth-posts.



HEINRICH SCHWEITZER,

OF NEW YORK, N. Y.

PROCESS OF MAKING DENTAL TOOTH-POSTS.

Application filed December 30, 1909.

T 0 all whom it may concern:

Be it known that I, HEINRICH Sonwmr- ZER, a subject of the GermanEmperor, residing at New York, in the county of New York and State ofNew York, have invented a Process of Making Dental Tooth-Posts Useful inMounting Porcelain Crowns to Roots and to Bridges, of which thefollowing is a specification.

Figures 1 and 2 are cross sectional views of porcelain crowns from thebottom of which the impressions are to be taken. Fig. 3 is the crosssection of an impression pattern for mounting a crown upon a bridge.Fig. 4 is the lateral view of a completed pattern for mounting a crownto a tooth root, made up of the metal shank and wax impressions. Fig. 5is the cross section of an impression pattern exposing the head of themetal skeleton, a, the shank, 0, around which the wax, (Z, is placed,and the apical enlargement, b, of the skeleton on the other end of theshank. Fig. 6 is the lateral view of the complete and perfect cast toothpost ready for use. Fig. 7 is a cross sectional view of a tooth rootwith the reamed canal opening, the letter, f, indicating the apex of theroot.

In the process of making a cast bottom or base backing for mounting ofporcelain crowns to roots, ordinary pins were used as pivots for thefixation of the crown in the tooth root, to which pins only the crownbottom was cast. These pins do not fit snugly in the crown opening nordo they fit tightly in the enlarged root canal opening, and if ever theydo fit in one or the other of these parts, they never fit tight at thesame time in both when ready for cementing. It is desirable to have notonly the root-surface on one side and the crown bottom-on the other sideimprinted in a cast bottom attachment of a crown, but also to haveincluded in the impression the crown-opening and the root canal opening.

In order to obtain a sharp impression of all the parts mentioned, Iconstruct impression points consisting of a metal skeleton, around whichthe impression wax is placed. The metal skeleton in this toot-h postimpression pattern consists of a shank, 0, with a head part, a, on oneend and an enlargement, b, on the other end. This enlargement b, ispractically called apical enlargement of the metalskeleton. The shank,0, originating in the center of the enlargement b, is representedSpecification of Letters Patent.

Patented Dec. 6, 1910.

Serial No. 5355M.

by a wire piece around which the wax for taking the impression isplaced.

The head parthas a size corresponding in shape to the innermostpart ofthe bottom opening of porcelain crowns. It prevents change of shape ofthe waximpression when the porcelain crown is removed. The enlargement,b, on the other end of the shank of the skeleton is supposed to enterthe enlarged root canal and therefore is of a shape corresponding to theinnermost part of the enlarged root canal opening. The surface 6 Fig. 5forms the boundary for the impression wax toward the end of the rootcanal opening. It prevents change of shape of the wax impression,holding the wax in position upon the shank when crown andimpression-pattern are removed from the root. It helps greatly to removethe wax from the canal opening.

The wax is readily shaped around the skeleton by the manufacturer andfits approximately to the parts, all that is to be done by the operatingdentist is, to soften the wax tooth post in warm water and press it homein the root canal and upon the root surface, using the crown on top asimpression tray.

If in taking apart the wax impression comes out with the crown andsticks to the porcelain crown, it can be easily removed by grasping theenlargement, Z), which is left free of wax, and pulling the porcelaincrown apart. If it sticks to the root after removal of the crown, bygrasping the head part, a, at its side walls with a pair of pin pliers.

The shank is thin enough to allow the entrance of the cast metal allaround, especially on account of the peculiar central position of theshank in the head part, a, and in the enlargement, Z), so that it iscentrally located in the invested mold, and after casting in the castpost.

Having now fully described my invention I claim:

The method of making a tooth post by surrounding a metal shank with itsenlarged ends with wax, taking impressions with it of the openings inthe crown, and in the natural root, and then using the same as a patternin casting the complete tooth post.

HEINRICH SCI-IWEITZER. lVit-nesses JOHN P. DAVIS, A. H. DAVIS.

